Behind the Acronym: CMOS

Behind every Xperia smartphone is some pretty powerful technology and behind that technology are some pretty smart engineers. Xperia Z5 features a brand new 23MP Exmor RSTM for mobile sensor and we’ve been speaking to one of our top camera engineers, Kensuke Mashita, to help explain what this means and why we make such a big noise about the sensors in Xperia cameras.

Go behind the acronym with one of the world’s leading camera engineers:

1) Can you give us a basic overview of what an image sensor does and how it works?

In the most basic terms, an image sensor captures the light that comes through the camera lens; it is sensitive to light in the same way that film is, but uses digital technology instead to turn light into electrons.

2) Can you talk about Sony’s Exmor RTM CMOS sensor technology?

Our Exmor R TM CMOS sensor is designed in a way that makes it highly sensitive
to light, which enables it to work well in low-light without giving too much noise (noise causes loss of detail).

Sony’s Exmor RTM CMOS sensor improves imagery performance as it has a back illuminated structure that improves the efficiency of how it captures and records light.

4) What are the challenges that you have to take into account when designing a sensor for a smartphone camera, particularly in comparison to DSLR?

The main challenge is size. If you cram too many smaller pixels into a small sensor designed for a phone, the quality of the image is affected which is evident when shooting in low-light. Put simply, this is similar to the way owls need big eyes to see in the dark – the bigger the sensor the bigger the pixels can be; also known as “pixel pitching”.

Generally speaking less pixels in a sensor means you can have larger pixels (photo diodes) and better quality in low-light. The challenge is in trying to balance the resolution needed without gaining ‘noise’ in low light. This balance is a huge consideration when designing a sensor for smartphones.

5) In what ways is the sensor in Xperia Z5 the same and in what ways is it different to one in a DSLR?

The general sensor technology is similar, but as well as the bigger size of DSLR sensors, DSLR’s have more space and require more processing power to process the image from a larger sensor. In Xperia Z5, there is less physical space, but the smaller sensor requires less processing power. As demand for higher resolution in small sensors increases, we’ve worked hard to optimise as powerful a processor as possible in the small space capacity of a phone.

6) Is Xperia Z5 able to integrate Sony’s Exmor RS TMCMOS sensor better than other smartphones that use it?

The camera in Xperia Z5 is a unique offering in the smartphone market. We have drastically increased the ability and efficiency of this technology to enable the fastest and most reliable autofocus from the Exmor RS TM CMOS in a phone.

Look out next month as we again go behind the acronym with another of the world’s leading smartphone engineers. Let us know what feature you’d like us to put under the lens in the comments or by getting in touch on Twitter.